Oil resistant rubber composition

ABSTRACT

A rubber composition containing epichlorohydrin homopolymer with various compounding ingredients which composition exhibits extraordinary physical and chemical properties under adverse conditions. The composition is compounded to withstand degradation where exposed to oil, water and brine at temperatures in excess of 250*F. and pressures as high as 4,000 pounds per square inch.

United States Patent 1 1 1111 3,882,060 Guzy 1 May 6, 1975 1 1 OIL RESISTANT RUBBER COMPOSITION OTHER PUBLICATIONS 1751 Inventor: Raymnd Guzy, Grove Eitingon et 61., -Chem. Abs. 67, 915205, (1967).

Insulation/Circuits Directory Encyclopedia, June/July [73] Assignee: Borg-Warner Corporation, Chicago, 9 Pag 15 452. 160

111. Hercules Chem. Co,,-Techn. Data Bulletin on Herchlor PRH-l, Series 3,5,8 & 9.

[22] Fned' 1973 Cure System for Hydrin 100 Elastomers, (B. F. Good- 121] Appl. NOJ 415,572 rich).

52 11.5. C1. 260/37 AL; 166/242; 166/244 (3; (31313 [58] Field Int. Cl... C08g 51/04; C08g 51/08; E211) 17/14 of Search 260/2 A, 2 EP, 79, 37 AL; 166/244 C, 242

Reierences Cited UNITED STATES PATENTS Assistant Examiner-H. H. Fletcher Attorney, Agent, or FirmRichard J. Schlott [57] ABSTRACT A rubber composition containing epichlorohydrin homopolymer with various compounding ingredients which composition exhibits extraordinary physical and chemical properties under adverse conditions. The composition is compounded to withstand degradation where exposed to oil, water and brine at temperatures in excess of 250F. and pressures as high as 4,000 pounds per square inch.

3 Claims, No Drawings OIL RESISTANT RUBBER COMPOSITION BACKGROUND OF THE INVENTION Many rubber compositions have been provided for 5 sitions for insulation of electrical cables, components in armored cables and the like. The oil industry has attempted to find a rubber compound that would not only be resistant to water, brine and oil, but one that would withstand those high pressures and high temperatures found at the bottom of an oil well. In some instances the pressure at the bottom of an oil well is as high as 4,000 psi and the temperature exceeds 250F. Though some of the desired properties were prevalent in prior rubber compositions, some compositions that would withstand the high pressures and temperatures would tend to disintegrate in the presence of some of the oil and brine components found at the base of an oil well.

SUMMARY OF THE INVENTION The instant invention provides a rubber composition having an epichlorohydrin homopolymer rubber base with certain compounding ingredients combined therewith which is capable of withstanding high temperatures and pressures and will maintain its structural integrity and useful physical properties upon exposure to oil, water and/or brine at temperatures up to and exceeding 250F. and pressures as great as 4,000 psi. Materials closely related to the present invention are disclosed in our copending application Ser. No. 272,253, filed July 17, 1972, now US. Pat. No. 3,817,908. The instant invention employs a different curing system to produce improved environmental resistance.

The epichlorohydrin rubber used to prepare the present composition is a poly(alpha-chloro-propylene oxide) homopolymer such as is sold by Hercules Inc. under the trademark Herclor H. The epichlorohydrin rubber is preferably a high molecular weight polymeric material wherein the molecular weight exceeds 200,000.

The compounding ingredients used to prepare the rubber composition include a Group VIII metal dialkyldithiocarbamate, for example, nickel dibutyl di- 50 thiocarbamate; a basic heavy metal phosphite, for example, basic lead phosphite; phenothiazine; an aliphatic dicarboxylic acid, for example, azelaic acid, suberic acid, sebacic acid and the like; a Group IE or [IE methyl dithiocarbamate, zinc diethyl dithiocarbamate or cadmium diethyl dithiocarbamate, and imidazole. The aforementioned components are essential parts of the curing system for the rubber.

In the curing system, the amount of each component previously mentioned may be varied. For example, the Group VIII metal dialkyldithiocarbamate may be added in an amount of l to 2 parts by weight per 100 parts by weight of epichlorohydrin rubber. The basic heavy metal phosphite may vary from 5 to 20 parts (preferably 10-15 parts) per 100 parts by weight of the epichlorohydrin rubber. The phenothiazine may vary from I to 2 parts (preferably 1 part) per 100 parts by weight of the epichlorohydrin rubber and the dicarboxylic acid may be from 4 to 6 parts per 100 parts by weight rubber. The Group 18 or [18 metal dialkyldithiocarbamate is added in very small amounts such as from 0.125 to about 0.2 parts per 100 parts by weight of rubber and the imidazole will vary from 1 to 2 parts per 100 parts by weight of rubber.

The rubber composition may also, of course, include processing aids and fillers. The processing aids that may be used without causing a detrimental effect on the rubber composition are sorbitan monoesters such as sorbitan monostearate, alkyl cellosolve esters and emulsions of ethylene waxes. In order to retain the highly beneficial effect of the rubber composition, it is preferable that the processing aids be added in relatively small amounts, such as l to 10 parts per 100 parts by weight of rubber.

Fillers that may be also used in the instant rubber composition include carbon black, diatomaceous earth, clays, silica, calcium carbonate and the like. The filler may be added in amounts from about 10 parts to about parts per parts by weight of rubber present and, of course, the specific amounts will vary depending on the desired or required mechanical properties of the end product. If the fillers are increased above 50% by weight of the rubber in the composition, the processing becomes exceedingly difficult. The preferred fillers are carbon black and silica.

Examples of specific formulations are set forth hereinbelow in TABLE I. All parts in TABLE I are by weight and the specific rubber compositions were made by compounding the epichlorohydrin rubber on a two roll laboratory mill. The compounding ingredients were incorporated by mill mixing for about 30 minutes. The compounded rubber was molded and cured at 345F. for about 45 minutes and post cured in a circulating oven at 300F. for about 3 hours. The cured rubber was cut into specimens of H16 X k X 1% inches. The specimens were placed in a high pressure vessel and the vessel was filled with the test liquid, sealed, pressured to 4000 psi with nitrogen gas and placed in an oven at 275F. for 7 days. In Table II, the percentage of volume change on exposure to different liquids is listed.

TABLE I Examples Components 1* 2* 3 4 5 6 7 8 Parts Parts Parts Parts Parts Parts Parts Parts Epichlorohydrin- Ethylcncoxide Copolymer 100 Epichlorohydrin Homopolymer I00 I00 100 I00 I00 100 I00 Nickel dibutyl dithiocarbamate 1.0 1.0 2.0 2.0 1.0 1.0 1.0 1.0 Basic Lead Phosphite 20.0 15.0 15.0 10.0 10.0 10.0 100 Red Lead 7.5

TABLE 1 Continued Examples Components 1* 2* 3 4 5 6 7 8 Parts Parts Parts Parts Parts Parts Parts Parts Phcnothiuzinc |.0 i 1 1.0 1.0 1.0 1.0 1.0

Azclaic Acid 4 0 n0 6.0 4.0 4.0 4.0 4.0

Copper dimcthyl di thiocarhamatc 125 I25 (I Z .12 125 125 Cadmium Dicthyl dithiocarbamate v s 4 A lfl'lldklZUlL? KH 1 1 1.5 1,0 2,0 2.0 1.0 1.0 1.0 2.0

Silica i W 2.0 10 10 10 10 HA1; Black A 3.0 55 311 30 30 30 MT Black w 125 i w ISAF Carbon Black 50 d if i A W Sorhitim Mono stcaratc 1.0 i 1.0 T0 1.5 1.5 1.5 1.5

Dibutox ethoxyethyl ndipatc A 0.5 .0 1.0 7.5 1.0 1.0

Polyethylene emulsion 1.0 0.5 1.0 0.5 0.5 0.5 05

Tricthylcnc Glycol Dimcthyl ether 20.0 i w W 4 Recommended Commercial Rubber Formulations (Prior Am 1 l llmidsmlc RE is lmidalmlc on t pc KF. clay. supplied by Hercules Chemical (orpumlion TABLE I1 Volume Change on Exposure to Water, Brine and Oil Seven Days at 275F. and 4000 psi 1 2 3 4 5 6 7 x "A 70 L70 71 "/0 Brine Exposure 10.0 1.32 8.1 3.12 065 -4.7 0.29 0.77

Oil Exposure 12.5 4.6 20.5 2.7 12.5 2.0 0.4? 0.49

Examples 4. 5, 6. 7 and 8 are illustrative of the present I claim:

invention. The test data shown in Table 11 indicate that l- An epichlorohydrin homopolymer rubber c0mpothe epichlorohydrin homopolymer rubbers comsition capable of being cured and then capable of withpounded and cured in accordance with the instant inf 4,000 P Pressure b27501? for at b 7 y vention are remarkably resistant to deterioration in the wlth less than abbm 5% Volume Swen from bl'me P' pmsgnce f Oil and brine, even at elevated tempera sure and less than about 5% volume change from 011 extures and extreme pressures. The compositions of Ex 531d P F compvnsed of about 100 parts amples l and 2, it will be noted, are inferior with re- 4 by f of an eplchbmhydrm homopolymer rubber spect to sensitivity to brine. Example 3 contains insuffr having agmolecular m elfcess 2 about cient filler which results in high volume swell in oil and l2 parts by we'ght of mc kel dlthmcarbamte, in water. Further, in Examples 48 inclusive, i.c., those about 10-15 parts b we'ght F lead phnsphltei within the limits of the instant invention. are more re- -U part by f l phfmothlazmei about 46 parts sistant to volume change in oil and brine. In particular by weght of an ahpbanc dmrboxyhc acfdiabout 0-125 the optimum materials represented by examples 7 and m Parts by Welght of a l f y dlthlocarbamate 8 exhibit only very minor volume changes under these d q from the gmup conlstmg P coppef q' extreme conditions dithiocarbamate and cadmium diethyl dlthiocarba- As the levels of fillers and processing aids are varied, mate; about 1 2 Parts by weght of l "mdazolei and sensitivity to brine and oil exposure is changed, as for from about 10 to about 50 Pf! by ig Ufa finer example 4 with high filler loadings and example 6, with lecied from the group Conslstmg of slbca and Carbon an increased level of processing aids. Although cornpob|aCksitions exhibiting the least change in volume swell are The Composlbon bf 31mm 1 b f P preferred, formulations exhibiting somewhat greater alds Selected b the group conslstlng 0f sbl'bllan sensitivity to these environments may find restricted monosteamte qibuwxyethoxyethyl adlpate and P application in less extreme environments and are inethylene bmulslbns added an amount f from eluded within the broadest scope of the instant invenabout Parts y Weight P 100 P y Welght of tion. rubber.

The compositions of the instant invention are espe- I epicblombydri" rubber composition Contain cially useful for gasketing, sealing and Coating materials mg 100 parts by weight epichlorohydrm homopolym for use in applications such as cable jacketing, connec 6() about 1.0 part by Weight n ckel dibutyl dithiocarbators. and casing sealants in oil well production equipmate, about 10 Parts y Wfiflght basil; lead P P p about 1.0 part by weight phenothiazine, about 4.0 parts Though the invention has been described with rey Welghl l l iC ac about .125 parts by weight copspect to specific compounding ingredients for the epi p dime hyl dithiocarbamate, about 1.0 part by weight chlorohydrin rubber. it is well understood by those imidazole, about 10 parts by weight silica, about 30 skilled in the art that the invention may be broader than specifically illustrated without departing from the spirit of the invention. The scope of the invention is defined by the claims which are appended hereto and made a part hereof.

parts by weight carbon black, about 1 .5 parts by weight sorbitan monostearate, about 1.0 part by weight dibutoxy ethyoxyethyl adipate, about 0.5 part by weight polyethylene emulsion therein. 

1. AN EPICHLOROHYDRIN HOMOPOLYMER RUBBER COMPOSITION CAPABLE OF BEING CURED AND THEN CAPABLE OF WITHSTANDING 4,000 PSI PRESSURE AT 275*F. FOR AT LEAST 7 DAYS WITH LESS THAN ABOUT 5% VOLUME SWELL FROM BRINE EXPOSURE AND LESS THAN ABOUT 5% VOLUME CHANGE FROM OIL EXPOSURE, SAID COMPOSITION COMPRISED OF ABOUT 100 PARTS BY WEIGHT OF AN EPICHLOROHYDRIN HOMOPOLYMER RUBBER HAVING A MOLECULAR WEIGHT IN EXCESS OF 200,000; ABOUT 1-2 PARTS BY WEIGHT OF NICKEL DIBUTYL DITHIOCARBAMATE; ABOUT 10-15 PARTS BY WEIGHT OF BASIC LEAD PHOSPHITE; ABOUT 1 PART BY WEIGHT PHENOTHIAZINE; ABOUT 4-6 PARTS BY WEIGHT OF AN ALIPHATIC DICARBOXYLIC ACID; ABOUT 0.125 TO 0.2 PARTS BY WEIGHT OF A DIMETHYL DITHIOCARBAMATE SELECTED FROM THE GROUP CONSISTING OF COPPER DIMETHYL DITHIOCARBAMATE AND ; ABOUT 1-2 PARTS BY WEIGHT OF A IMIDAZOLE; AND FROM ABOUT 10 TO ABOUT 50 PARTS BY WEIGHT OF A FILLER SELECTED FROM THE GROUP CONSISTING OF SILICA AND CARBON BLACK.
 2. The composition of claim 1 wherein processing aids selected from the group consisting of sorbitan monostearate, dibutoxyethoxyethyl adipate and polyethylene emulsions are added in an amount of from about 1-10 parts by weight per 100 parts by weight of rubber.
 3. An epichlorohydrin rubber composition containing 100 parts by weight epichlorohydrin homopolymer, about 1.0 part by weight nickel dibutyl dithiocarbamate, about 10 parts by weight basic lead phosphite; about 1.0 part by weight phenothiazine, about 4.0 parts by weight azelaic acid, about .125 parts by weight copper dimethyl dithiocarbamate, about 1.0 part by weight imidazole, about 10 parts by weight silica, about 30 parts by weight carbon black, about 1.5 parts by weight sorbitan monostearate, about 1.0 part by weight dibutoxy ethyoxyethyl adipate, about 0.5 part by weight polyethylene emulsion therein. 